It's discrete just like info that one has 19001.18 bucks in their account rather than 19000. Precise yes, useful not very.
I guess ‘behavior and appearance’, mentioned in another comment, are the more practical dimensions, but I still wonder how useful the distinctions are.
Perhaps you mean to say that strains should be defined in a fuzzy manner? If so, from my very limited knowledge of systematics, they already are.